Memristors (also known as ReRAMs) have been proposed among the leading candidates for high density storage of information. Understanding the physical mechanisms that govern memristive switching has become a field of intense research. In particular, such physical mechanisms are difficult to measure experimentally. For instance, transmission electron microscopy studies are the de facto characterization technique but typically only provide a single, post-mortem filament state snapshot. Furthermore, despite its fundamental importance, filament temperature evolution is all but unknown experimentally. Accordingly, additional methods to understand resistive states and filament states are desired.